The agency abused its discretion when it preserved these provisions of the hours of service rule, said Public Citizen, Advocates for Highway and Auto Safety and the Truck Safety Coalition.

The groups, joined by truck drivers Mildred Ball and Dana Logan, filed suit last week in the U.S. Court of Appeals for the District of Columbia Circuit.

This suit sets the stage for a legal showdown between trucking industry interests, the safety groups and the agency in the long-running battle over the rule.

American Trucking Associations and its allies have asked the court to strike four provisions of the rule, which is scheduled to take effect next July. They object to limitations on the restart, and to a driver break provision.

The agency has until October 24 to respond, and final briefs are due November 21. Oral arguments are not yet scheduled.

The safety groups say in their brief that the agency should have considered revoking the 34-hour restart, pointing out that the court has twice vacated that provision. And the limitations on the restart - it can be used only once a week and it must include two rest periods between 1 a.m. and 5 a.m. - do not make the provision safe, they said.

The agency also erred in its decision not to eliminate the 11-hour limit on daily driving, the groups said.

The agency was incorrect when it said it needs "compelling scientific evidence" that a 10-hour limit is cost-effective, they said. The agency's mandate to improve highway safety gives it all the authority it needs to make the change, they said.